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Tuesday 5 July 2011

Definition: Autosomal dominant deafness locus 64.

SMAC/DIABLO is a mitochondrial proapoptotic protein that is released from mitochondria during apoptosis and counters the inhibitory activities of inhibitor of apoptosis proteins, IAPs.

By linkage analysis and candidate screening, authors identified a heterozygous SMAC/DIABLO mutation, c.377C>T (p.Ser126Leu, refers to p.Ser71Leu in the mature protein) in a six-generation Chinese kindred characterized by dominant progressive nonsyndromic hearing loss, designated as DFNA64.

SMAC/DIABLO is highly expressed in human embryonic ears and is enriched in the developing mouse inner-ear hair cells, suggesting it has a role in the development and homeostasis of hair cells.

Authors used a functional study to demonstrate that the SMAC/DIABLO(S71L) mutant, while retaining the proapoptotic function, triggers significant degradation of both wild-type and mutant SMAC/DIABLO and renders host mitochondria susceptible to calcium-induced loss of the membrane potential.

Their work identifies DFNA64 as the human genetic disorder associated with SMAC/DIABLO malfunction and suggests that mutant SMAC/DIABLO(S71L) might cause mitochondrial dysfunction.


- Functional Mutation of SMAC/DIABLO, Encoding a Mitochondrial Proapoptotic Protein, Causes Human Progressive Hearing Loss DFNA64. Cheng J, Zhu Y, He S, Lu Y, Chen J, Han B, Petrillo M, Wrzeszczynski KO, Yang S, Dai P, Zhai S, Han D, Zhang MQ, Li W, Liu X, Li H, Chen ZY, Yuan H. Am J Hum Genet. 2011 Jun 29. PMID: 21722859